Wood Heat II

We've made the decision. We're going to go wood heat this winter, and in a big way.

We've put down a deposit on a high-efficiency stove insert for one of our fireplaces, which will cost about $3,300 installed. In two weeks, the installer comes to inspect our layout and give us a final estimate. Then, if all goes well, two weeks after that we'll have our new fireplace installed.

The unit we're buying is the biggest, baddest stove insert we could find. The manufacturer claims that it puts out up to 75,000 BTU/hour, and it is EPA rated at less than 2 g/hour of particulate emissions (aka smoke). In other words, once this baby gets fired up, it will be putting out a significant fraction of the heat our main furnace generates, and with almost nothing visible out the chimney.

Now that we've made the decision to go wood, we're facing some practical issues.

First off, we don't really know how much wood we'll need for the winter. A friend with some experience suggests that we'll probably go through two or three cords. My best guess is that we've got between one and two cords currently in our yard, and much of that is very low quality. There are other trees in our yard we're planning to cut down, but it is too late to harvest trees this fall and have the firewood properly seasoned (dried) in time for burning this winter.

A cord of firewood, by the way, is a stack 4' wide, 4' high, and 8' long, or 128 cubic feet. It could also be called a truck, since a cord is about the maximum amount of firewood you can carry in a heavy-duty pickup truck.

There are a few other places I can draw upon for firewood this winter. My parents may have some extra, and every now and then you can spot people trying to give away excess firewood on Craigslist. With my trusty red pickup, I should be able to pick up a half-cord here and there. With luck I may be able to avoid actually spending money on firewood this winter, but that remains to be determined.

Another practical issue is going to be actually running the fireplace 24x7 in the coldest part of the winter. The manufacturer claims it will run 3-12 hours on a load of wood, but the 12 hours is only achievable at the lowest heat setting. On high, we'll have to reload it every 3 hours at least. In practice, that means that we'll be able to get at most 4 loads of wood (12 hours of burning) on weekdays when we're not home, and 6 loads on weekends (18 hours of burning). That gives us 900,000 BTU/day on weekdays, and 1,350,000 BTU/day on weekends. On the coldest days of the winter, our furnace is probably running about 75% of the time, which equates to something like 2,430,000 BTU/day. So on the coldest days of the winter, at best we may be able to provide half our heat from the fireplace.

Fortunately most of the winter is not as cold as the few days when we get a big cold snap.

I'm also thinking about ash disposal. Burning several cords of firewood--even very efficiently--will generate a significant amount of ash. Once cool, the ash can simply be thrown away in the regular trash, or worked into the vegetable garden (it is used to treat acidic soil). But it can't be put in the trash hot, and we won't be shutting the fireplace down for the 24-48 hours needed for the ash to cool before cleaning. So we'll need to find a fireproof ash container, such as a steel trashcan or bucket.

Steel buckets are astonishingly hard to find these days. Everything is made of plastic.

Now for the good news (good for us, anyway): our local gas company just announced whopping price increases for the month of October (prices are set month to month depending on market prices). The October price is 14% above the September price, and 77% above last October's price. Even at that level, the prices don't reflect all of the spike on the commodities markets, so I assume there's some major hedging going on (in Minnesota, the gas utilities are required to sell the gas at cost to customers; they make their profit on the distribution cost). So we can probably expect additional price increases for the next few months.

That means that the $3,000 cost to heat our home with gas this winter is looking realistic, and possibly even low. So the wood heat really could save us a bundle of money, and paying for the fireplace insert in under two years looks like a good bet.

We'll just hope for warm weather until we get it installed.